This application relates to the art of thermal protectors and, more particularly, to thermal protectors used in electric circuits. The invention is particularly applicable to thermal cutoffs and PTC devices, and will be described with particular reference thereto. However, it will be appreciated that the invention has broader aspects, and that components other than thermal cutoffs and PTC devices can be used.
One common type of thermal protector is known as a thermal cutoff, and includes a pellet that melts at a predetermined temperature to open a pair of contacts and interrupt a circuit.
Another known type of thermal protector is a device made of a material having a positive temperature coefficient of resistance, also known as PTC device. Within a certain narrow temperature range, the electrical resistance of such devices jumps sharply, and substantially switches off current to the system being protected.
For certain purposes, it is desirable to have the protection of both a thermal cutoff and a PTC device. Therefore, it would be desirable to have a unitary package incorporating both types of thermal protectors. This would allow rapid and economical installation of only one assembly in a circuit, while affording dual protection by both thermal protectors.